The invention relates to a semiconductor component and to a corresponding fabrication/mounting method.
Power semiconductor components are only provided with a small number of pins (generally two to three) compared to IC components. The useability of a component of this type is greatly dependent on how efficiently the heat loss generated in the semiconductor component can be dissipated to the outside. This is because if the heat loss cannot be dissipated sufficiently quickly via the small number of pins, in the most serious scenario the semiconductor component can be destroyed. With surface-mounted semiconductor components, this problem can be counteracted by placing the semiconductor component on a lead frame which is pressed around it and then for its part soldered to a printed circuit board. The heat loss generated in the semiconductor component can then be efficiently dissipated via the lead frame and the soldering contact formed between lead frame and printed circuit board. A further problem with semiconductor components of this type resides in the punctiform connection locations for the load current. These are usually connected to the pins of the housing which surrounds the semiconductor component or lead frame by bonding wires and on the one hand limit the current-carrying capacity and homogeneity of the current distribution on the semiconductor component and on the other hand lead to additional, undesirable leakage inductances. The punctiform connection locations can even become the limiting variable in the semiconductor component with regard to the application of load current to the semiconductor component under surge current or overload conditions.
The abovementioned problems arise in particular with standard housings (for example TO-263 or D-Pak). Furthermore, the costs of these housings and corresponding processes for mounting the semiconductor components in the housings represent cost factors which are by no means negligible. SMD housings or axial housings which do not have a cooling connection that can be soldered to the printed circuit board in turn have the drawback that the heat loss which is generated cannot be dissipated quickly enough, since this can only be achieved via the small connection legs of the housings. Moreover, axial housings can only be arranged on the front surface of a printed circuit board, which greatly restricts the flexibility of the mounting arrangements.
The problems which have been outlined above are to be explained further in the text which follows on the basis of specific examples and with reference to FIG. 1. FIG. 1 shows a semiconductor component 1 which is mounted in various housings (a first to fifth housing 2a to 2e). In a first embodiment 3a, the semiconductor component 1 is contact-connected both on its top side and on its underside, the underside of the semiconductor component 1 bearing directly on a contact layer 4, an extension of which leads out of the first housing 2a as first connection leg 5a. The top side of the semiconductor component 1 is connected via a bonding wire 6 to a contact-connection region, an extension of which leads out of the first housing 2a as second connection leg 5b. In the second embodiment 3b, the top side of the semiconductor component 1 is contact-connected by means of a contact layer 7 which forms an extension of the second connection leg 5b. In the third embodiment 3c, the semiconductor component 1 is contact-connected exclusively at its top side, i.e. the contact layers connected to the first and second connection legs 5a, 5b are both positioned on the top side of the semiconductor component 1, whereas the back surface can be soldered to the printed circuit board directly rather than via a connection leg during subsequent mounting.
In the fourth embodiment 3d, the top side of the semiconductor component 1 is contact-connected by a metal structure 8 which simultaneously represents the top side of the fourth housing 2d. The underside of the semiconductor component 1 can be soldered directly to a printed circuit board via corresponding contacts 9 which lead out of the fourth housing 2d. In the fifth embodiment 3e, the top side of the fifth housing 2e is “nestled” directly against the semiconductor component 1 and, as in the previous exemplary embodiment, serves for contact-connection of the top side of the semiconductor component 1, it being possible for the underside of the semiconductor component 1 to be soldered to a printed circuit board via contacts 9 together with the ends 10 of the top side of the housing 2e. 
All the embodiments 3a to 3e described above have the drawback that mounting the semiconductor component is a relatively complex operation. Furthermore, the costs of the housings 2a to 2e are high. Also, at least in the first to third embodiments 3 to 3c, it is difficult for the heat loss generated in the semiconductor component 1 to be dissipated via the first and second connection legs 5a and 5b. 
The object on which the invention is based is to provide a semiconductor component and a method for fabricating/mounting it which avoids the drawbacks described above.
To achieve this object, the invention provides a method for fabricating/mounting semiconductor components as described in patent claim 1. Furthermore, the invention provides a semiconductor component as described in patent claim 14. Advantageous embodiments and refinements of the subject matter of the invention are given in the subclaims.